I have a '99 4x4 w/ a 360 w/ 82K, and on cold start ups, like after it's been sitting over night, when i start the engine, theres a high pitched whining that gets higher, and faster if i rev the engine a little. The whining goes away after the engine warms up, but it sounds like it's coming from a belt, and if it is, which belt is it?

 

I'd say the serpentine belt...I had the the same problem and didn't take care of it in time and the darn thing just broke..Its not expensive but if you don't take care of it right away then be prepared to walk home. (I did[:@]) Good luck.